Adjustable stroke mechanism for tufting machines

ABSTRACT

This disclosure relates to tufting machines and in particular an adjustable crankshaft for varying the needle stroke in such machines which includes means for changing the position of the connecting rod relative to the crankshaft bearing blocks and the axis of the crankshaft whereby the crank throw will be changed and thus the needle stroke. An adjustable counterweight mechanism is also provided which may be adjusted in the same manner as the connecting rod but opposite thereto which results in a balanced crankshaft drive mechanism.

0 United States Patent 11 1 1111 3,839,972 Scott et al. Oct. 8, 1974[54] ADJUSTABLE STROKE MECHANISM FOR 1.391113 10/1921 Hudson 74/603 T GMACHINES 1,765,927 6/1930 Maier 112/220 3,665,873 5/1972 Wittler 112/79A [75] Inventors: Jimmie D. Scott; Randel P. Smith,

both of Hamllton Tenn Primary Examiner-James R. Boler [73] Assignee: TheSinger Company, New York, Attorney, Agent, or Firm-Marshall J. Breen;Chester NY. A. Williams, Jr.; Julian Falk [22] Filed: May 3, 1973 21Appl. No.: 356,875 [57] ABSTRACT This disclosure relates to tuftingmachines and in particular an adjustable crankshaft for varying theneedle [52] Cl 112/79 43 6 1 stroke in such machines which includesmeans for 51] I t Cl 20 changing the position of the connecting rodrelative to [58] d A the crankshaft bearing blocks and the axis of the agg 17 1 j crankshaft whereby the crank throw will be changed A 4 andthus the needle stroke. An adjustable counterweight mechanism is alsoprovided which may be ad- [56] References Cited justed in the samemanner as the connecting rod but UNITED STATES PATENTS Knous 1/1900Frost opposite thereto which results in a balanced crankshaft drivemechanism.

8 Claims, 6 Drawing Figures BACKGROUND OF THE INVENTION Most tuftingmachines built today have a needle drive mechanism which includes a maindrive shaft upon which is mounted a plurality of eccentric cam devices.These eccentrics drive the needle bar at a stroke which is dependentupon the amount of eccentricity relative to the main axis of thecrankshaft. It will be apparent that as requirements for greater needlestrokes are encountered, the eccentric cam devices must be made largeras the length of the needle stroke varies directly with the amount ofeccentricity. There comes a point when the size of the eccentric cams istoo great to be practical and such machines are thus limited in thelength of the needle stroke which can be obtained. Further, when usinglarge eccentrics there is a problem of machine stability and inachieving versatility in needle stroke adjustment. With the advent ofpopularity in shag type or long nap fabrics there has been a demand fora tufting machine which can provide a relatively long needle stroke, sayup to three inches, while at the same time being readily adjustable sothat lower nap fabrics can be produced on the same machine. It is thepurpose of the present invention to provide such a machine.

GENERAL DESCRIPTION OF THE INVENTION In the present invention, a tuftingmachine having a main drive shaft is constructed such that said maindrive shaft is in the form of a crank shaft. The crank shaft is providedwith a number of crank portions whose axes are offset from the axis ofthe main shaft itself. The connecting rods which drive the needle bar inits reciprocating motion are each connected to a crank portion so thatthe length of the stroke of the needle bar is controlled by the degreeof offset of the axis of the crank portions. In order to vary the strokeof the needle bar the crank shaft is constructed such that the distancebetween the axis of the crank portions and the axis of the main shaftitself may be varied. In order to vary the distance between theaforementioned axes, the crank portions are readily moveable relative tothe axis of the main shaft thus varying the distance of the throw of thecrank portions. The crankshaft is balanced by providing adjustablecounterweights which are provided adjacent each crank portion and whichare preferably adjustable in the same manner as the crank portion itselfbut in a direction opposite to the direction of offset of the crankportion. The counterweights are selected to offset vibrational effectswhich may be present due to the offset rotation of the crank portion.The crankshaft of the invention thus provides for a smooth running drivemechanism in a tufting machine and which is capable of providing arelatively wide range of needle strokes.

Accordingly it is one object of the invention to provide a novel andimproved tufting machine having a relatively wide range of selection ofneedle strokes.

It is another object of the invention to provide a novel and improveddrive shaft mechanism fora tufting machine.

It is a further object of the invention to provide a novel and improvedadjustable stroke crankshaft for a tufting machine.

It is an additional object of the invention to provide a novel andimproved adjustable crankshaft.

Other objects and advantages of the invention will be best understoodfrom the following detailed description of the invention with theaccompanying drawing.

DESCRIPTION OF DRAWING FIG. 1 illustrates a cross-sectional view of atufting machine embodying the present invention;

FIG. 2 illustrates an enlarged top plan view of a portion of oneembodiment of the crankshaft of the invention taken in the direction ofline 2 2 of FIG. 1.

FIG. 3 illustrates an enlarged front view of a portion of the crankshaftof FIG. 1 taken in the direction of line 3 3 of FIG. 1; and

FIG. 4 illustrates an exploded perspective view of a portion of theembodiment of FIG. 1; and

FIG. 5 is an enlarged top plan view of a portion of a second embodimentof the invention; and

FIG. 6 is an enlarged front view of a portion of the second embodimentof the invention.

DETAILED DESCRIPTION OF INVENTION Referring to FIG. 1, a tufting machine10 is illustrated as having a head portion 12 and a bedplate portion 14.Included in the head portion 10 is a needle mechanism which comprises aneedle bar 16 which supports a plurality of needles 18 for penetrating abase fabric F with yarns Y. The needle bar 16 is connected to a push rod20 which is driven in a reciprocating manner in a bushing 22 by aconnecting rod 24 in a manner which will be more fully describedhereinafter.

A looper mechanism is supported in the bedplate portion and includes aplurality'of loopers or hooks 26, one for each needle, operablysupported on a hook shaft 28 which is driven in an oscillating motion ina well known manner. The hooks 26 serve to pick up loops of yarn fromthe needles 18 on their downstroke and hold the loops during the returnstroke of the needles. A knife mechanism may be associated with eachhook 26 for cutting the loops in order to make cut pile tufted fabricsand includes a plurality of knives 30 each operably supported on anoscillating knife shaft 32 which is suitably oscillated in timedrelationship with the hooks to cut the loops. Feed rolls 34, 36, 38 and40 are provided for feeding the base fabric F across a needle plate 42so that as the fabric is advanced through the machine a plurality ofrows of loops or cut loops will be formed in the base fabric. Themechanism thusfar described is conventional in tufting machines.

The main drive mechanism for the needle mechanism in tufting machines isgenerally provided in the head portion 12 and includes a main shaft 44.which is generally operably connected to a prime mover such as anelectric motor (not shown). As briefly described above, mainshaftshaving eccentrics or cams have been used with connecting rods supportedthereon so that as the main shaft rotates the connecting rods willimpart a reciprocating motion to a push rod connected thereto. Thelength of the stroke of the push rod, to which the needle bar isconnected, is dependent upon the amount of eccentricity of the cam. Asthe requirements for longer needle strokes become more desirable, sayfor example when tufting shag type or long nap fabrics, it becomesnecessary to increase the size of the cams. However, as the mass of thecams becomes larger certain disadvantages appear such as requirementsfor increasing the size of the head portion of the machine toaccommodate the cams and unbalancing or undesirable vibrationalcharacteristics. As a result it is not always practical to use a cam oreccentric drive when building a machine to be operated at high speed andfor tufting shag fabrics.

In accordance with the present invention these disadvantages areovercome. In the embodiment of present invention shown in FIGS. 24, themain drive shaft 44 is generally in the form of a crank shaft comprisinga plurality of stub shafts 46 journaled in bearing blocks 48 suitablyfastened to a portion of the machine head 12 by bolts or the like asillustrated in FIG. 1. As best shown in FIG. 4, each stub shaft 46 has areduced end portion 50 on each end thereof in which is formed a slot orgroove 52 to form a pair of spaced tab or tongue portions 54 and 56. Thetab portions 54 and 56 each have a plurality of holes 58 and 60,respectively, for receiving bolts 62 to which nuts 63 are fastened onthe outside thereof in the usual manner. As will be seen in FIG. 4, thebolts 62 are preferably inserted from opposite sides, although the boltscould also be inserted from the same side.

With further reference to FIG. 4, in particular, it will be seen thateach connecting rod 24 has a connecting rod bearing head portion 64 inwhich there is journaled a connecting rod bearing shaft or crank portion66. Each such shaft 66 has a reduced portion comprising a tongue or tab68 on each end thereof in which there is drilled a hole 70 for receivingthe bolts 62. Each tab 68 is made to fit into a slot 62 in a stub shaft46 and the holes therein will mate with holes 58 and 60 of the adjacentstub shafts 46 so that the bolts 62 will pass through bothelements 46and 66 to fasten them together. It will be apparent from FIGS. 2, 3 and4 that the selection of the mating holes 58, 60 and 70 will determinethe distance between the axis of the stub shaft 46 and the connectingrod bearing shaft 66 or the eccentricity of the shaft 66 relative to theshaft 46. With the shaft 66 being connected to the bearing block 64 andthe connecting rod 24, the stroke of the connecting rod 24 and push rod20 will thus be determined by the relative location of the shafts 46 and66.

As the distance between the axes of the shafts 46 and 66 is increasedthrough adjustment, as described above, there may be a tendency for anincrease in vibration in the machine. In order to counteract theincrease in vibration a counterweight is provided between eachconnecting rod position and is constructed for attachment and adjustmentrelative to the stub shaft 46 in the same manner as shaft 66. Thus, forexample, in FIGS. 2 and 3 it will be seen that between each connectingrod 24 and shaft 66 there is a counterweight 72 which as illustrated inFIG. 2 is disposed for adjustment or positioning relative to the axis ofthe shafts 46 an equal amount but in an opposite direction to theadjustment or positioning of the shaft 66 in order to counterbalance theshaft 66. The ends of the counterweights 72 are formed with a tabconstructions 73 which is substantially the same as the similarconstruction on the shafts 66. For every change in position of a shaft66 there will be an equal and opposite change in position of thecounterweight 72 whereby the entire shaft will always be in balance andrelatively free of vibration. This will permit operation at relativelylong strokes and at high speeds which has heretofore not been readilypossible.

Referring now to FIGS. 5 and 6, wherein like numerals refer to likeelements, each connecting rod 24 and shaft 66 construction isessentially the same as in the first embodiment. In the embodiment ofFIGS. 5 and 6 the counterweight construction comprises a pair ofcounterweights 74 and 76 which are attached to the same tab elementconstruction 54, 56 and slot 52 as the particular shaft 66 with whichthe counterweights are associated. In other words the counterweights arenow disposed at a connecting rod position on the shaft instead ofbetween adjacent connecting rod positions. As illustrated thecounterweights 74 and 76 are connected to the tab elements by bolts 62and nuts 63 and are adjustable relative to the connecting rod positionto counterbalance the offset of the connecting rod from the center ofthe shaft axis. This construction permits a change in eccentricity andthus needle stroke to be made relatively rapidly at a single positionfor each connecting rod and counterweight.

Because the counterweights and connecting rods are located at the sameposition along the length of the shaft, the portions of the shaftbetween connecting rod positions can be of relatively simpleconstruction. Thus, as seen in FIGS. 5 and 6, the shaft portions 78which extend between adjacent connecting rod positions are ofsubstantially uniform diameter along their length and through thebearing blocks 48. Their end portions 80 and 82 and groove 84 areconstructed the same as that described in the first embodiment withrelation to shaft 46, namely end portions 54 and 56, but there are onlyhalf as many such constructions since the adjustable counterweights havebeen removed from positions between adjacent connecting rod positions.As a result the construction of the second embodiment is relativelysimple in construction and enables relatively simple and rapidadjustment.

From the above description and illustration in the drawings, it will beapparent that a relatively wide range of stroke adjustment is availablein tufting machines incorporating the structure of the presentinvention. For example, a needle stroke ranging from one inch to threeinches has been readily attainable with this mechanism and the machinehas been operable at relatively high speeds even with the maximum needlestroke. It will further be seen that the shaft construction of theinvention does not require a relatively large area in the machine headas would be the case if a standard type tuftingmachine eccentricmechanism were used to accomplish the same needle stroke range. Further,it is a relatively simple matter to change the needle stroke withoutrequiring a lot of machine down time as was previously the case. Allthat is required is removing the head cover and loosening and moving themachine screws for each shaft 46 and 66, repositioning the same and thecounterweights and re-tightening the machine screws. The degree ofneedle stroke will of course be governed by the relative position of theshafts 46 and 66 with the maximum needle stroke occuring at the greatestdistance between the axes of the shafts 46 and 66.

While applicant has set forth his invention in its preferred form itwill be apparent to those skilled in the art, that various modificationsand changes may be made without departing from the spirit and scopethereof as set forth in the appended claims.

What is claimed is:

1. In a tufting machine having an adjustable stroke needle mechanism andmeans for initiating reciprocating motion of said needle mechanismincluding a connecting rod means operably connected to said needlemechanism, a drive shaft operably connected to a source of power forinitiating rotary motion of said drive shaft, said drive shaft includinga first shaft member for receiving thereon a connecting rod means, aplurality of second shaft members each being journaled in a bearingblock in coaxial relationship, said first shaft member having its endportions disposed between facing end portions of adjacent second shaftmembers and having its axis offset relative to the axis of said secondshaft members, interconnectable means fixed on the end portions of saidfirst shaft member and on said facing end portions of said second shaftmembers, and means for adjustably securing the interconnectable means ofsaid first shaft member to adjacent interconnectable means of saidsecond shaft member facing end portions for adjusting the position ofsaid first shaft member relative to its associated second shaft memberssuch that the offset of the axis of said first shaft member can beradially changed relative to the axis of said second shaft memberswhereby for each change in the position of said first shaft memberrelative to said second shaft members there will be a change in strokeof the needle mechanism.

2. In a tufting machine as recited in claim 1 further comprising meansfor counterbalancing said drive shaft including counterweight means, andmeans for adjusting the position of said counterweight means tocounterbalance the relative offset position of said first shaft memberand its connecting rod means.

3. In a tufting machine as recited in claim 1 wherein saidinterconnectable means lie in planes parallel to a plane containing theaxes of said first and second shaft members, and said securing means liein planes perpendicular to the planes of said interconnectable means.

4. In a tufting machine as recited in claim 3 wherein theinterconnectable means on one of said first and second shaft memberscomprises a pair of spaced tongues, and the interconnectable means onthe other of said first and second shaft members comprises a tabreceivable in the space between said tongues, said securing meanscomprises a plurality of spaced holes through said tongues, and at leastone hole in said tab, and bolt means extending through a selected holein each pair of tongues and through the hole in the corresponding tab.

5. In a tufting machine as recited in claim 4 further comprising meansfor counterbalancing said drive shaft including counterweight means andmeans for adjustably connecting said counterweight means to one of saidtab and tongue pair.

6. In a tufting machine as recited in claim 2 wherein said counterweightmeans are adjustably connected to said second shaft members.

7. In a tufting machine as recited in claim 4 wherein said spacedtongues are formed on the second shaft members, and said tab is formedon the first shaft member.

8. In a tufting machine as recited! in claim 7 including means forcounterbalancing said drive shaft, said counterbalancing meanscomprising counterweight means, a tab having a hole formed on saidcounterweight means receivable in the space between the tongues. andbolt means extending through the hole in the tab and through a hole inthe pair of tongues spaced from said selected hole.

1. In a tufting machine having an adjustable stroke needle mechanism andmeans for initiating reciprocating motion of said needle mechanismincluding a connecting rod means operably connected to said needlemechanism, a drive shaft operably connected to a source of power forinitiating rotary motion of said drive shaft, said drive shaft includinga first shaft member for receiving thereon a connecting rod means, aplurality of second shaft members each being journaled in a bearingblock in coaxial relationship, said first shaft member having its endportions disposed between facing end portions of adjacent second shaftmembers and having its axis offset relative to the axis of said secondshaft members, interconnectable means fixed on the end portions of saidfirst shaft member and on said facing end portions of said second shaftmembers, and means for adjustably securing the interconnectable means ofsaid first shaft member to adjacent interconnectable means of saidsecond shaft member facing end portions for adjusting the position ofsaid first shaft member relative to its associated second shaft memberssuch that the offset of the axis of said first shaft member can beradially changed relative to the axis of said second shaft membErswhereby for each change in the position of said first shaft memberrelative to said second shaft members there will be a change in strokeof the needle mechanism.
 2. In a tufting machine as recited in claim 1further comprising means for counterbalancing said drive shaft includingcounterweight means, and means for adjusting the position of saidcounterweight means to counterbalance the relative offset position ofsaid first shaft member and its connecting rod means.
 3. In a tuftingmachine as recited in claim 1 wherein said interconnectable means lie inplanes parallel to a plane containing the axes of said first and secondshaft members, and said securing means lie in planes perpendicular tothe planes of said interconnectable means.
 4. In a tufting machine asrecited in claim 3 wherein the interconnectable means on one of saidfirst and second shaft members comprises a pair of spaced tongues, andthe interconnectable means on the other of said first and second shaftmembers comprises a tab receivable in the space between said tongues,said securing means comprises a plurality of spaced holes through saidtongues, and at least one hole in said tab, and bolt means extendingthrough a selected hole in each pair of tongues and through the hole inthe corresponding tab.
 5. In a tufting machine as recited in claim 4further comprising means for counterbalancing said drive shaft includingcounterweight means and means for adjustably connecting saidcounterweight means to one of said tab and tongue pair.
 6. In a tuftingmachine as recited in claim 2 wherein said counterweight means areadjustably connected to said second shaft members.
 7. In a tuftingmachine as recited in claim 4 wherein said spaced tongues are formed onthe second shaft members, and said tab is formed on the first shaftmember.
 8. In a tufting machine as recited in claim 7 including meansfor counterbalancing said drive shaft, said counterbalancing meanscomprising counterweight means, a tab having a hole formed on saidcounterweight means receivable in the space between the tongues, andbolt means extending through the hole in the tab and through a hole inthe pair of tongues spaced from said selected hole.